This invention relates to a system and method for rapidly and electronically scanning long lengths of one or more yarns, and displaying measured qualities of a large number of selected lengths of the yarn in a fabric pattern to assist in the evaluation of the effects of the quality variations on the quality of fabric which potentially would be produced from the one or more yarns.
There are numerous quality tests for yarns and the fabric they will produce. One such test is for the general appearance of the fabric. This test is accomplished by weaving or knitting the subject yarns into a fabric sample. Yarn quality defects and effects, such as color inconsistencies, width inconsistencies, hairiness, slubs, broken ends, and other novelty effects can thereby be judged as they will affect fabric quality, unarguably the most critical aspect of the yarn. The occurrence of yarn defects in close proximity on the fabric, of undesirable defect patterns, of a multitude of marginally acceptable yarn defects creating an unacceptable fabric defect, can be visually observed and quantified. This test has been standardized as ASTM D2255/90 and ASTM D2255. It has become the accepted method for predicting the quality of fabric to be produced from entire lots of sampled yarns based on the probability that unacceptable fabric defects will be observed in a sample of this size.
Fabric quality will be affected by other factors as well as yarn quality, such as loom defects. Because looms and knitting machines intended for high production runs of fabric cannot practically be interrupted for the running of small test runs, as reasoned below, the machines used for test sample runs tend to be smaller, older, worn, or obsolete models whose results would be generally unacceptable for producing marketable fabric. Variations in tension on one or more yarn strands during weaving or knitting will cause fabric variations that might be read as resulting from poor yarn quality. Sinusoidally occurring loom inconsistencies will cause recurring fabric faults whose regularity may not be recognized in the small test sample, and may therefore be read as resulting from poor yarn quality. Other loom deficiencies and also ambient temperature and humidity conditions may affect fabric quality independently of the quality of the yarn from which it was produced. Obviously, the grading of yarn in fabric samples is a somewhat qualitative process, leaving the possibility that one grader might judge a sample quite differently than another grader, that the subject sample might not accurately represent the fabric to be produced, or that defects will be missed as a result of the small sample size.
Other drawbacks to the current grading system are that it requires the actual weaving or knitting of a fabric sample, or winding the yarn on a board, which requires specialized equipment and specialized operator training, or an actual loom or knitting machine. Test samples can be produced using an instrument such as a Fiber Analysis Knitter (FAK) like that manufactured by Lawson-Hemphill, Inc., of Central Falls, R.I. Looms and knitting machines are huge and complicated machines requiring many manual settings and adjustments independent to each run. These machines cannot practically fit within small quality labs and require operator expertise not typical of lab personnel. A significant amount of the time taken to produce a fabric run is in the set-up of the machine. Each fabric pattern requires a different loom set-up procedure. Looms are quite expensive to purchase and operate, take up substantial floor space, and must be used efficiently in the production of marketable fabric in order to justify their high cost. For reasons of time and cost, the practice of setting-up a production loom to run a few small test samples of a particular fabric would be impractical. Test samples are generally run on smaller weaving or knitting machines which are more practical for this application even though those tend to be slow and to have outputs which may not be fully indicative of production fabric.
Further drawbacks to the current test sample making method is that many actual yarn sample spools are required to run even these small test samples, and the yarn waste percentage is very high on such a short run.
It can readily be seen that the current fabric grading method is very slow, inaccurate, labor intensive, highly judgmental and expensive.
It is therefore the object of this invention to provide a system and method for electronically displaying simulated fabric including one or more measured qualities of a large number of yarn lengths, measured from one or more yarn samples, to assist in predicting fabric quality as it would be affected by those measured yarn qualities.
The term xe2x80x9cdisplayxe2x80x9d as used herein is meant to encompass human-viewable computer outputs, such as a CRT or a printer output, and/or a machine-interpretable data set-such as the data from which a visible display could be derived, depending on the possibilities in each given use. As explained herein, the data set is created from measurements, or representations of such measurements, taken along one or more lengths of yarn.
This invention results from the realization that a fabric sample evaluation test may be accomplished electronically by scanning long lengths of one or more yarn samples from one or more yarn cones and arranging and displaying the long lengths of yarn as a number of interwoven shorter lengths in a typical fabric pattern to electronically simulate the manual fabric test sample currently in use, and by representing different measured yarn qualities with display attributes such as their actual image, display line width or length, shades of grey, colors, or numerical or other values, to allow the visual evaluation of the simulated fabric as done manually with fabric samples, and also allow electronic yarn gradings and actual counts of faults or events in the yarn and fabric.
It is a further object of this invention to provide such a system and method that is less expensive to accomplish than the manual system. The need for valuable loom time is virtually eliminated. Fabric simulations will most often be sufficient to judge yarn lot acceptability.
It is a further object of this invention to provide a system for predicting the quality of finished goods made of fabric woven or knitted from a particular yarn sample.
It is a further object of this invention to provide such a system and method that is quicker than the manual system. Yarn measurements can be converted to simulated fabric almost instantly. Loom set-up time and run time is eliminated.
It is a further object of this invention to provide such a system and method that is easier and less labor intensive than the manual system. Once a yarn length is measured, manual labor to provide the simulated fabric display can be reduced to a few keystrokes.
It is a further object of this invention to provide such a system and method that provides results which can be more accurately quantified, and thereby eliminate human judgement. The number of yarn faults on a fabric sample can be readily established. The proximity of yarn faults/qualities, and their relationship within a predetermined fabric zone can be evaluated and quantified or stored. These results can then be compared to an established tolerance or reference to eliminate the subjectivity of the current grading process. One or more simulated fabric images could be displayed simultaneously on a CRT screen to compare one simulated fabric to another, or to a standard. One yarn could be displayed simultaneously woven into one or more patterns, or woven with other yarns.
It is a further object of this invention to provide such a system and method that allows for the grading of a greater quantity of yarn cones and fabric test samples than is currently accomplished. Any possible arrangement of any number of woven or knitted yarns can be accomplished rapidly. Worst-case scenarios can be located and the statistical probability of their occurrence can be instantly calculated.
It is a further object of this invention to allow rapid and inexpensive evaluation of yarn in many known fabric patterns. A single yarn sample may be measured and its representation may be electronically xe2x80x9cknittedxe2x80x9d into a particular knit pattern, or that representation may serve as both the weft and warp yarns in a particular weave pattern. One yarn samples"" representation may be used continuously as the weft of a simulated woven fabric patch, while a multitude of other yarn sample""s representations are used as the warp yarns in the same pattern. From one or a few small samples of yarn, a large number of fabric patterns may be evaluated, saving time, labor, and cost.
It is a further object of this invention to eliminate the waste associated with the current ASTM test sample system, and to simplify inventory control. Fabric samples being simulated instead of actually produced require only those yarn samples being measured. No yarn is wasted at the loom. Once measured, the data file for a given sample can be used repeatedly. Yarn lengths can be instantly xe2x80x9cwovenxe2x80x9d with other measured yarns in any known pattern to find an acceptable match for otherwise unacceptable lots of yarn. Yarn lots can be xe2x80x9cfingerprintedxe2x80x9d with their measurement data and filed electronically. Then, when a fabric grade requirement necessitates that yarn within certain qualities be selected, yarn lot fingerprint files can be searched electronically to locate from inventory acceptable yarn lots, and instantly provide displays of simulated weavings. Yarn lots can be quantitatively graded according to their effect on fabric quality, or on fabric quality for certain patterns. A yarn lot could be graded A for one given weave pattern, and B for another pattern, based solely on the results of simulated weave analysis, with no actual weaving having been done. The invention can thereby serve to determine the best application for a given yarn. A yarn with certain fault characteristics may be unacceptable for one use, but perfectly acceptable for another use. The system could thereby help to determine the most appropriate use for a particular yarn sample, reducing rejection and waste. The system can be adapted for on-line measurement of yarn under production (this is very important), allowing for tagging of a yarn run with it""s fingerprint data as it is produced, simplifying inventory control and eliminating the need for post-production measurement.
Yarn lengths can be imaged with a video camera, and the data stored as computer files which can be manipulated to enhance or to filter out selected qualities. Then the files can be interwoven to provide a realistic image of the resulting fabric. Images can be distorted electronically to imitate the twists and bends of actual weaving or knitting. Image portions can be deleted to imitate passage behind other images. The image could be displayed in three dimensional fashion so that the effects of twists and non-linearities on the yarns in the fabric, and the effect on the fabric as a whole by such non-linearities, can be displayed.
Results from the simulated fabric evaluation can be used to correct production faults. Corrections can be electronically simulated as well to determine their effects in improving defective yarn. Video color adjustments could be made, for instance, to instantly determine the results of die color changes on the final fabric.
Feedback from the electronic system can be used not only as an end-product evaluation tool, but also as an in-process correction tool. When adapted for on-line measurement, weaves can be instantly simulated and quantified, with or without a display, and the results fed instantly back to the appropriate production equipment to correct yarn production and reduce rejection rates. Yarn production will become more efficient and thereby faster.
This invention contemplates measurement of any measurable yarn quality, and use of such measurements for the stated objectives. Such measurable qualities include (but are not limited to), diameter and its average, coefficient of variation and standard deviation, evenness, hairiness, the ratio of core-to-hair thickness, twist, color, neps, and thick and thin areas.
The described concepts of yarn quality measurement and representation determination can be used to automatically, by use of a computer, xe2x80x9cgradexe2x80x9d the yarn itself, or an electronically-created xe2x80x9cfabricxe2x80x9d. This would not require a visible display or printout. Such grading can be accomplished by programming the computer so that types, locations, and sizes of faults (called xe2x80x9ceventsxe2x80x9d) that result in a particular grade are known. The computer could include a neural network programmed to weight events properly, and combine weightings properly, to simulate human judgment used in manual grading. The neural network would originally be input with information from expert human inspectors regarding the relative importance of each particular event, and of patterns of events, in determining yarn/fabric grade.
Types, quantity, location and patterns of events all contribute to quality determination. Patterns can be determined by electronically xe2x80x9cdividingxe2x80x9d the display into display areas or cells that are portions of the whole, or possibly the entire, data set. Quantities of event(s) in the cells can be counted, and evaluated cell-by-cell if desired. Unacceptable event patterns could be determined based on a concept as simple as any cell with a given percentage more than the average cell event quantity for any one or more particular events, or by more complex cell comparisons. A simple example of this concept could be that if a certain event occurs in any two vertically or horizontally adjacent cells, there is an unacceptable pattern.
This invention can be utilized to simulate the effect of a traditional yarn clearer on the measured yarn, and also to dynamically instruct a downstream yarn clearing device to remove certain measured events to upgrade the measured yarn. The first goal can be accomplished by electronically deleting certain measured events, and potentially evaluating the difference in yarn or fabric grade accomplished by such electronic clearing. The second goal can be accomplished by making the necessary measurements upstream of a yarn clearing device, and electronically determining the measured event(s) that needed to be cleared to create a desired yarn/fabric grade.
For Dynamic Yarn Clearing (DYC), a reservoir of a sufficient length of yarn between the measurement point and the clearer could be used to both provide the necessary time delay after measurement for the system to make the necessary calculations, and also to allow the comparison of multiple events occurring over the reservoir length of yarn as it would affect the grade. For example, a particular event could be acceptable if it occurred no more than once every two hundred meters. A two hundred meter reservoir could be used, and if two such events were measured over this length, only one would be cleared. This system would save time and cost over traditional clearing, in which the clearer is set to remove each and every fault of a certain width and length. In the case above, such a traditional clearer would remove both events, when only one needed to be removed for the desired grade, or for the intended yarn use. The dynamic yarn clearing of this invention thus measures one or more measurable yarn qualities, as well as the length of yarn measured, and makes clearing decisions based on both.